1. Field
Exemplary embodiments relate to photo-detection devices. More particularly, exemplary embodiments relate to unit pixels having ring-shaped structures, photo-detection devices including unit pixels having ring-shaped structures, and methods of measuring distances using unit pixels having ring-shaped structures.
2. Description of the Related Art
An image sensor is a photo-detection device that converts optical signals including image and/or distance (i.e., depth) information about an object into electrical signals. Various types of image sensors, such as charge-coupled device (CCD) image sensors, CMOS image sensors (CISs), etc., have been developed to provide high quality image information about the object. Recently, a three-dimensional (3D) image sensor is being researched and developed which provides depth information as well as two-dimensional image information.
The three-dimensional image sensor may obtain the depth information using infrared light or near-infrared light as a light source. The three-dimensional image sensor may have a lower signal-to-noise ratio (SNR) and lower sensitivity than a conventional two-dimensional image sensor, which results in incorrect depth information being obtained.